关于NUC123从LDROM切换到APROM启动问题

只看该作者 · 2013-12-21 09:08

请大家指教一下，要做的是，当程序检测到USB没有插入，则从APROM中启动。下面这样写怎么跳不进去？
//======================================================
// USB Floating Detect
//======================================================
void UsbFdt(void)
{
uint8_t u8FLODET = USBD->FLDET.FLDET;

_DRVUSB_SET_EVF(EVF_FLD);

if (u8FLODET)
{
      /* USB Plug In */

if (g_u8UsbState & USB_STATE_ATTACHED)
{
      /* Do nothing if it is already attached */
return;
}

/* Update USB state */
g_u8UsbState = USB_STATE_ATTACHED;

/* Init the end points */
UsbCfg();

      /* Enable USB and enable PHY */
      _DRVUSB_ENABLE_USB();
}
else
{
      /* USB Un-plug */

      /* Update USB state */
g_u8UsbState = USB_STATE_DETACHED;

udcOnLine = 0;

      /* Disable USB, Disable remote weak up, and disable PHY */
      _DRVUSB_DISABLE_USB();
   /* Boot from AP */
RoughDelay(0x200000);
      RESET_TO_AP();//CPU复位，从AP启动,此函数放于主函数的最前面是有用的
}
}